Driving mechanism for portable drills or similar tools.



J. A. BRADLEY. DRIVING MECHANISM FOR PORTABLE DRILLS OR SIMILAR TOOLS.

APPLICATION FILED 1330.2, 1909.

1,040,867, Patented Oct. 8, 1912.

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J, A BRADLEY.

DRIVING MECHANISM FOR PORTABLE DRILLS 0R SIMILAR TOOLS.

APPLICATION FILED DEC. 2, 1909.

Patented @013. 8 1912.

2 SHEETS-$HEET Z.

INVENTOR m. (X QmdQuIK IS WA M (mm W i m I: 55 E s i I/ u UNITED STATES PATENT OFFICE.

JAMES A. BRADLEY, OF PITTSBURGH, PENNSYLVANIA, ASSIGNUIR 0F ONE-HALF TO HENRY C. IDIGBY, OF PITTSBURGH, PENNSYLVANIA.

Specification of Letters Patent,

Patented Oct. 8,1912.

Application filed necember 2, 1909. Serial No. 530,8?5.

To all whom it may concern:

Be it known that 1, JAMES A. BRADLEY, of Pittsburgh, in the county of Allegheny and State of Pennsylvania, have invented a new and useful. Improvement in Driving Mechanism for Portable Drills or Similar Tools, of which the following is a full, clear and exact description, reference being ha to the accompanying drawings, forming part of this specification, in which Figure 1 is a vertical longitudinal section through the motor and its casing, and showing one form of my improved mecha nism. Fig. 2 is a section on the line 11-11 of Fig. 1. Fig. 3 is a similar view on the line IIIIII of Fig. 1. Fig. 4 is a plan View of a portion of the cooling fan; and Fig. 5 is a plan view of the tool spindle and the reducing gear frame carried thereby.

This invention relates to driving mechanism for portable drills or similar tools, and is designed to provide a cheap and efiicient mechanism of the character described which can readily be assembled and taken apart for repairs.

Another object of my invention is to pro vide an improved ball bearing arrangement for the tool spindle and driving mechanism which will be wholly contained in the gear casing which is removably secured to the motor casing.

Still another object of my invention is to provide planetary gearing in which the gear carrying frame is rigidly secured to the tool spindle or formed integrally therewith, and driven by means of a pinion on the motor shaft.

Still another object of my invention is to provide a slip connection between the stationary rack and the gear case to provide means for automatical y disconnecting the gearing, or to allow it to rotate idly when the tool is crowded beyond a predetermined point.

The precise nature of my invention will be best understood by reference to the accompanying drawings, which will now be described, it being premised, however, that various changes may be made in the details of construction and general arrangement of parts without departing from the spirit and scope of my invention as defined in the appended claims.

In the drawings, the numeral 2 designates a motor casing containing a motor 3.

4 is the shaft of the motor, having a pinion 5 at its lower end. This pinion 5 is provided with a screw threaded boss 5 arranged to engage screw threads in the lower end of the shaft 4:.

6 is a gear casing, which is connected to the motor casing by the through bolts 7. Resting on ball bearings 8 within the gear casing is a tool spindle 9, which is provided at its upper end with a lurality of arms 10, in' each of which is Journaled a short shaft 11. Mounted on the upper end of each of these shafts is a gear wheel 12 which meshes with the pinion 5, and mounted on the lower end of 'each of these shafts 11, is a pinion 13 which meshes with a rack 14, held between flanges 15 on the motor casing. This rack 14 is fixedly held with relation to the motor casing by means of the spring pressed plunger 16. The lower end of the spindle is screw threaded and is arranged to receive the lower ball-bearing member 17 of the ball-bearings 18, which member retains the spindle from upward movement in the gear casing. The ball-bearing member 17 is locked in its adjusted position by the lock nuts 18, one of which is provided with a set screw 19 to retain it in its adjusted position. The upper end of the spindle 9 is provided with ball-bearings 2O arranged to support the motor shaft 1. The upper end of the motor casing 2 is provided with a screw threaded orifice arranged to receive the fixed nut 21 the inner face of which is bored outto receive a plurality of collars 22, the inner collar surrounding the end of the hollow shaft 1 of the motor.

23 is the shank of a cutting tool which is inserted in the spindle 9.

21 is a short rod which extends through the bore of the pinion 5 and the members forming the ball bearings 20 into the interior of the spindle 4.

26 is a screw threaded stem, the threads of which engage the nut 21. The upper end of this screw is provided with a center 27 and a hand wheel 28. The screw and rod are arranged to eject the tool from the spindle 9.

29 is a fan which is secured to the lower end of the m tor spindle and is arranged to be rotated thereby to pass a current of air through the motor casing to keep the parts cool.

The various parts as shown in Fig. 1 are in position to rotate the tool 23, and when the drill is placed in position the center 27 is adapted to engage the proper center in a yoke which is placed around the work to be drilled or reamed. The current is turned on, and the rotation of the motor rotates the gears 12 through the medium of the pinion 5, which in turn rotates the gears 13, and through the medium of the stationary rack 14-, the spindle 9, together with the arms, the shafts 11 and the gears attached thereto, rotate within the motor casing and actuate the drill. If the drill should be forced into the work to such an extent as to be crowded beyond the point at which the resistance on the rack would overcome the pressure exerted against the spring pressed plunger 16, the plunger 16 will be forced outwardly, the rack 14 will be rotated and the tool 23 will remain stationary.

When it is desired to remove the gears, the bolts 7 are removed from the casing and the motor casing is lift/edfrom the gear casing. If it is desired to remove the spindle from the gear casing, the nuts 18- and the ball-bearing members 17 are removed from the end of the spindle; and the spindle, together with all of the gears can be removed from the casing.

The advantages of my invention result from the provision of a spindle which is provided with a plurality of arms or a frame connected thereto and arranged to carry the reducing gears, together with the internal rack which is fixedly held in connection with the gear casing.

Another advantage results from the provision of a slip connection between the stationary rack and the gear casing to allow the rack to be rotated when the tool is overcrowded. By this PTOVQdOD l overcome the injury to the drills or tools, which are frequently overcrowded by men who are not thoroughly familiar with the use of the tools, and I also provide means whereby the burning out of the motor is prevented in case a workman attempts to force the tool beyond the limit of the motor.

I am aware that it is old to use fuses in the line circuit, which are blown before one rent passes through the motor to burn it up.

This arrangement is expensive, and also necessitates the calling of an electrician to insert a new fuse. With my arrangement the connection between the rack and the easand the work proceeded with. otill another advantage results from the provision of the ball-bearings for the spindle wholly within the gear casing, which bearings can readily beadjusted without removing any of the mechanism from either of the casings. By slacking the set screw 19 and adjusting the member 17, together with lock nuts 18, the ball bearings can readily be adjusted to take up Wear.

ll claim:

1. In a portable drill or similar tool, a

motor having a shaft, a tool spindle, reducing gears carried by the spindle, a casing for the reducing gears, a rack mounted in guides in said casing, a driving pinion on the motor shaft, the reducing gears on the spindle engaging the pinion on the motor shaft and the rack, and a spring pressed plunger for connecting the rack to the casing, said plunger being arranged to disconnect the rack when a predetermined resistance has been reached, substantially as described.

2. In a portable drill or similar tool, a motor having a shaft, a tool spindle, reducing gears carried by the spindle, a casing for the reducing gears, a circular guide in the casing, a rack mounted in said guide, a slip connection between the casing and the rack, and a driving pinion on the motor shaft, the reducing gears on the spindle engaging the pinion on the motor shaft and the rack, substantially as described.

3. In a portable drill or similar tool, a motor casing, a motor having a shaft contained therein, a gear casing connected to the motor casing, a tool spindle journaled within the gear casing, the motor shaft being journaled in the motor casing and in the spindle, and means on the spindle on opposite sides of the spindle journal to secure the tool spindle in the gear casing and to prevent longitudinal movement thereof; substantially as described.

l. lln a portable drill or similar tool, a motor casing, a motor having a shaft contained therein, a gear casing secured to the motor casing, a tool spindle journaled in the gear casing ball bearings on opposite ends of the spindle bearing in the gear casing, means to secure the tool spindle in the hearing to prevent longitudinal movement thereof, and ball bearings on the end of the tool spindle arranged to support the motor shaft; substantially as described.

5. ln a portable drill or'siinilar tool, a motor having a hollow shaft, a tool spindle in line with the motor shaft, actuating connections between the motor shaft and the tool spindle, a tool supported in the end of the tool spindle, a plunger in the rear of the tool spindle, and means in the motor shaft for feeding the spindle longitudinally when moved in one direction and for ejecting the tool when moved in the other direo tion, said feeding means also forming means for advancing the plunger in the tool spindle to eject the tool; substantially as described.

6. In a portable drill or similar tool, a motor having a hollow shaft, a tool spindle in line with the motor shaft, actuating connections between the motor shaft and the tool spindle, a tool supported in the end of the tool spindle, a plunger in the rear end of the tool spindle, and a screw in the motor shaft, said screw being arranged to feed the JAMES A. BRADLEY.

Witnesses:

1 Jnssn B. HELLER, H. M. CORWIN. 

